The present invention relates to an occupant protection system for protecting an occupant of a vehicle such as a car in an emergency situation such as a collision. More specifically, the present invention relates to an occupant protection system for protecting an occupant with a seatbelt system having an airbelt.
An airbelt seatbelt system is known in which part of a seatbelt webbing is constructed of an airbelt that expands in the event of a car emergency. One example of such an airbelt is disclosed in Japanese Unexamined Patent Application Publication No. 2003-312439 in which part of a shoulder part and part of a lap part are each constructed of an airbelt.
A seatbelt system that has a pretensioner that retracts one end of a seatbelt webbing to apply pretension thereto is also well known. One example of such a pretensioner is disclosed in Japanese Unexamined Patent Application Publication No. 2001-287622 in which both a shoulder part of the seatbelt webbing and a lap part thereof have their own pretensioners. The shoulder pretensioner is activated first, and after a lapse of a predetermined period of time (e.g., 10 ms), the lap pretensioner is activated.
Conventional seatbelt systems typically include a seatbelt webbing that passes through a tongue. The seatbelt webbing has a shoulder part, which is composed of a noninflating standard belt, and a lap part, which has an airbelt. If the system is provided with a pretensioner at the shoulder part and if the pretensioner and the airbelt inflator are activated at the same time, a first tension is generated by the retraction of the shoulder part by the pretensioner and a: second tension is generated by the shortening force of the lap part by the inflation of the airbelt. Unfortunately, however, in the vicinity of the tongue, the tension generated by the retraction of the shoulder part competes against the tension generated by the shortening force of the lap part. As a result, the retraction of the shoulder part by the pretensioner often is not transmitted to the lap part.
Accordingly, the present invention has been made in light of the aforementioned problems. An object of the present invention to provide an occupant protection system, which includes a shoulder part constructed of a standard belt and a lap part at least part of which is constructed of an airbelt, which has a pretensioner that retracts the shoulder part in a car emergency, and which sufficiently transmits the retraction of the shoulder part to the lap part.